The reaction of methanol and ammonia to produce methylamines, comprising a mixture of mono-, di- and trimethylamine, is a well known reaction. The reaction product is an equilibrium mixture with about 35 wt % of the reaction product consisting of monomethylamine (MMA), 27 wt % dimethylamine (DMA), and 38 wt % trimethylamine (TMA) produced at a temperature of 350.degree. C., 1 atmosphere pressure and an ammonia to methanol ratio (N/R) of 3.5. Substantial process efforts have been made for the development of processes which would alter the product slate resulting from the reaction of methanol and ammonia. Process variables influencing product slate, although limited, include space time, ammonia to methanol molar ratio and temperature. Product slate modifications primarily have been made via shape selective catalysts such as zeolites.
Representative patents which illustrate various processes for the production of a methylamine reaction product having non equilibrium levels of MMA, DMA and TMA by the reaction of methanol and ammonia are as follows:
U.S. Pat. No. 4,485,261 discloses a process for the preparation of a methylamine reaction product rich in DMA and lean in TMA which comprises introducing a mixture of methylamines and ammonia to a porous; solid acid catalyst comprising silica, alumina, Y and X type zeolites, thereby forming a first reaction product and then subjecting at least a part of the reaction product to a catalytic reforming reaction in the presence of ammonia and a crystalline alumino-silicate having a pore size of 3 to 8 .ANG.. A variety of catalysts having a pore size of 3 to 8 .ANG. is set forth, and these catalysts include clinoptilolite, erionite, mordenite, chabazite and various synthetic zeolites. U.S. Pat. No. 4,205,012 discloses a process for producing amines by the reaction of an alkanol with ammonia, e.g., the manufacture of methylamines by the reaction of methanol and ammonia in the presence of an FU-1 zeolite, said FU-1 zeolite having essentially all of the sodium cations replaced by bivalent or trivalent cations.
U.S. Pat. No. 4,602,112 discloses a process for producing DMA in high selectivity by the reaction of methanol or dimethylether and ammonia in the presence of an acidic H-ZSM-5 zeolite catalyst.
U.S. Pat. No. 3,384,667 discloses the alkylation of ammonia in the presence of a dehydrated naturally occurring crystalline alumino-silicate catalyst having pores of a diameter permitting absorption of primary and secondary, but not tertiary, amine products. Examples of natural zeolites include ferrierites, chabazite, erionite and mordenite.
U.S. Pat. No. 4,737,592 discloses a process for producing a reaction product rich in DMA by reacting methanol and/or dimethylether and ammonia in the presence of an acidic zeolite catalyst selected from the group consisting of natural, H-exchanged and M-exchanged chabazites, each having a geometric selectivity index (GSI) greater than about 3. Alkali metal ions suited for exchange include sodium, potassium, rubidium and cesium.
U.S. Pat. Nos. 4,458,092; 4,398,041 and 4,434,300 disclose processes for producing methylamine by carrying out the reaction utilizing zeolite type catalysts. The '092 patent discloses the use of a highly acidic dehydrated alumino-silicate catalyst exchanged with a rare earth or hydrogen metal ion exchanged Y-zeolite. The '300 patent discloses the preparation of the amines using macroporous H-chabazite-erionite as the preferred amination catalyst. Anaconda chabazite-erionite was used as a specific catalyst and that catalyst system achieved high methanol conversion rates with minimal TMA production.
U.S. Pat. Nos. 4,254,061 and 4,313,003 disclose the production of a methylamine rich in MMA ('061) and DMA ('003). The '061 patent discloses the reaction of methanol and ammonia in the presence of mordenite, erionite, clinoptilolite, etc. to produce MMA, while the '003 discloses the reaction of MMA and ammonia in the presence of the '061 patent catalysts to produce a reaction product rich in DMA.
U.S. Pat. No. 4,082,805 discloses the production of amines by the reaction of C.sub.1 to C.sub.5 alcohols or ethers with ammonia in the presence of a crystalline alumino-silicate having the structure ZSM-5, ZSM-11 or ZSM-21.